Bug#915703: FTBFS: fails to correctly detect PETSc 3.10 version

[Drew Parsons]

Source: deal.ii
Version: 9.0.0-2
Severity: important

A build of deal.ii against PETSc 3.10 (currently in experimental) fails:

-- 
-- Include /home/drew/projects/mathlibs/build/test/deal.ii-9.0.0/cmake/configure/configure_3_petsc.cmake
-- Found PETSC_LIBRARY
-- Found PETSC_INCLUDE_DIR_ARCH
-- Found PETSC_INCLUDE_DIR_COMMON
-- PETSC_PETSCVARIABLES not found! Call:
--     FIND_FILE(PETSC_PETSCVARIABLES NAMES petscvariables HINTS / PATH_SUFFIXES conf lib/petsc/conf)
--   PETSC_VERSION: 3.0.2.0
--   PETSC_LIBRARIES: /usr/lib/x86_64-linux-gnu/libpetsc.so
--   PETSC_INCLUDE_DIRS: /usr/include/petsc;/usr/include/petsc
--   PETSC_USER_INCLUDE_DIRS: /usr/include/petsc;/usr/include/petsc
-- Found PETSC
-- Could not find a sufficiently modern PETSc installation: Version >=3.3.0 required!
-- DEAL_II_WITH_PETSC has unmet external dependencies.
CMake Error at cmake/configure/configure_3_petsc.cmake:122 (MESSAGE):


deal.ii appears to be detecting PETSc 3.10.2 as 3.0.2.

deal.ii's version of FindPETSC.cmake appears to be some monstrosity
that mangles PETSC_VERSION_MINOR violently instead of reading it cleanly from
petscversion.h. 

This bug will become serious (RC) once the petsc 3.10 transition
starts, which I want to trigger soon.

Drew


-- System Information:
Debian Release: buster/sid
  APT prefers unstable
  APT policy: (500, 'unstable'), (1, 'experimental')
Architecture: amd64 (x86_64)
Foreign Architectures: i386

Kernel: Linux 4.18.0-3-amd64 (SMP w/4 CPU cores)
Locale: LANG=en_AU.UTF-8, LC_CTYPE=en_AU.UTF-8 (charmap=UTF-8), LANGUAGE=en_AU.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash
Init: systemd (via /run/systemd/system)
LSM: AppArmor: enabled